Method of dyeing structures comprising acrylonitrile polymers



United States Patent fifice 2,740,687 Patented Apr. 3, 1956 BIETHOD OF DYEING STRUCTURES COMPRISING ACRYLONITRILE POLYMERS George E. Ham, Dayton, Ohio, assignor, by mesne assignments, to The Chemstrand Corporation, a corporation of Delaware No Drawing. Application February 1, 1952,

Serial No. 269,609

9 Claims. (Cl. 8-4) This invention relates to a method of dyeing structures or shaped articles comprising acrylonitrile polymers and more particularly to the dyeing of such structures with the acid-wool type dyestuffs. Polymers" as used through out the instant specification and claims is intended to include copolymers, terpolyrners, and blends thereof, said polymers containing at least 80% by weight of polymerized or copolymerized acrylonitrile in the polymer molecule.

By structures is meant shaped articles, such as yarns, films, filaments, fibers, strands, rods, tubes, bristles, fab rics, molded articles, and the like.

Acrylonitrile polymers containing a major portion of acrylonitrile are relatively insoluble, unreactive and hydrophobic materials. These characteristics make the dye ing of structures prepared from such polymers a diflicult problem. It is known that polyacrylonitrile and, in gen eral, acrylonitrile copolymers high in acrylonitrile cannot be dyed satisfactorily by conventional dyeing methods. Certain copolymers of acrylonitrile show improved re ceptivity for the various dyestuffs. For example, those copolymers of acrylonitrile which contain basic tertiary nitrogen can be dyed fairly satisfactorily with the acid wool dyestuffs using conventional conditions for applying those dyes, that is by treating the structures comprising the copolymers in or with an aqueous medium containing the selected acid dye and sulfuric acid as a dyeingas sistant. However, neither the depth of, shade obtained nor the extent of penetration of the dye into and through the cross-section of the polymer article is entirely satisfactory.

Accordingly, it is an object of the present invention to provide a'new process for dyeing structures prepared from acrylonitrile polymers. Another object of the pres ent invention is to provide animproved process for dyeing structures comprising acrylonitrile polymers which are receptive to the acid-wool dyestufis whereby the structures are dyed to deeper, more intense shadeswith complete, or substantially complete, penetration of the dye into and through the cross-section of the structure. Other objects and advantages of the present invention will be apparent from the description thereof hereinafter.

Inlge'ne'ral, the objects of the present vention are ac complished by treating the structure ormed from an acrylonitrile polymer with a dyeing medium containing, in addition to the acidtype 'dyestutf and the acid, such as sulfuric acid, acetic acid, and the like, a basic polymer orcopolyrner which comprises a vinyl substituted tertiary amine'or a salt thereof which is soluble in the said acids. As examples of the vinyl substituted tertiary heterocyclic amines which are useful in the practice of the invention, may be named polyvinylimidazole, polyvinylpyridine, co polymers of N-vinylimidazole, 2-vinylpyridine, alkyl-sub stituted vinylpyridines, vinylquinoline, vinylmercaptw benzothiazole, and the like, with polymerizable monoo'lefinic compounds such as acrylonitrile, styrene, vinyl chloride,'vinyl acetate, vinylidene chloride, dialkyl fume. rates','in which the alkylradical has up to four carbon atoms, the alkyl methacrylates and acrylates, wherein the alkyl radical has up to four carbon atoms, allyl chloroacetate, methallyl chloroacetate, and the like, etc. Examples of the salts are polyvinylpyridine hydrochloride, polyvinylpyridine sulfate, polyvinylpyridine phosphate, quaternary salts of polyvinylpyridine, vinylimidazole, vinylquinoline and vinylmercaptobenzothiazole, and in addition, poiymers of unsaturated chloroacetates quater nized with tertiary amines may be employed.

If desired, the dyeing media containing the vinyl substituted tertiary heterocyclic amines or salts thereof may be sprayed on the acrylonitrile polymer structures or the latter may be washed with the media and then heated. Preferably, however, the structures are' immersed in the dyeing media and then heated or the media may be at the desired temperature prior to immersion. Various structures, such as yarns, filaments, tubes, rods, and the like, may be dyed in a continuous manner by means of the present invention, and in fact, the dyeing procedure can be easily and readily worked in as an additional step in the process of manufacturing such structures.

The vinyl substituted tertiary heterocyclic amines and salts thereof are employed in the dyeing media in a con centration of about 0.10 to 10.0%, based on the weight of the structure. The temperature of the dyeing media may be varied between room temperature and approximately C., depending upon the type structure being dyed. Normally a temperature within the range of 60 to 100 C. is used. Temperatures as high as 100 to C. may be employed when a pressure vessel is used.

The present invention is of primary importance in dyeing structures formed from acrylonitrile polymers which do not have basic polymers or monomers incorporated therein. However, the invention also greatly increases the dyeability of acrylonitrile polymers which do have basic polymers or monomers incorporated therein.

While the present process is applicable to dyeing any of the type structures enumerated hereinbefore, for purposes of simplicity of description, the invention will be described as it is applicable to the dyeing of fibers, such term, as used herein, including staple fibers, filaments, threads, yarns, strands, and the like. It is to be understood that this is merely intended in' an illustrative sense and the invention is not to be limited thereby, but only insofar as the same may be' limited by the appended claims.

Among the structures which are readily dyeable in accordance with the process of the present invention, are those formed from polyacrylonitrile copolymers, such as binary and ternary polymers containing at least 80% by weight of acrylonitrile in the polymer molecule, or a blend comprising polyacrylonitrile or copolymers com prising acrylonitrile with from 2 to 50% by weight of another polymeric material, the blend having an overall acrylonitrile polymer content of at least 80% by weight. The phrase polymer comprising at least 80% of polymerized acrylonitrile as used herein is intended to include polymers and interpolymers, copolymers and blends in which the polymerized acrylonitrile is present in an amount of at least 80% by weight.

For example, the polymer may be polyacrylonitrile or a binary interpolymer comprising from 80 to 98% acrylonitrile and from 2 to 20% of another substance containing the ethylenic (:C linkage and interpolymerizable with acrylonitrile. Suitable monomers for interpolymerization with acrylonitrile are various olefinic monomers, such as vinyl acetate, styrene, alpha-methyl styrene, methacrylonitrile; acrylic, alpha-chloracrylic, and methacrylic acids; acrylamide and metbacrylamide; alphachloracrylamide or monoalkyl substitution products thereof; vinyl chloride, vinylidine chloride; various alkyl acrylates, alkyl methacrylates, alkyl furnarates', and alkyl maleates wherein the alkyl groups have up to four carbon atoms; N-virrylimidcs, such as 'N-vinyiphthalimide and N- vinylsuccinimide; vinyl-substituted tertiary heterocyclic amines, such as vinylpyridines and alkyl substituted vinylpyridines, for example 2-vinylpyridine and Z-mcthyl- 5-v'inylpyridine, N-vinylimidazole, etc., and other @C containing polymerizable materials. Or, the polymer may be a ternary interpo'lymer, for example products obtained by the interpolymerization of acrylonitrile and two or more of any of the monomers other than acrylonitrile enumerated above. More specifically, and preferably the ternary polymer comprises acrylonitrile, methacryloni'trile, and 2-vinylpyridine, or N-vinylimidazole. The ternary polymers preferably contain from '80 to 98% acrylonitrile, from 1 to of a vinylpyridine or a l-vinylim'idazo'le, and from 1 to 18% of another substance such as methacrylonitrile or vinyl chloride. In addition, the polymers which are readily dyeable by the instant process are blends of polyacrylonitrile or of a .binary interpolymer of 80 to 98% acrylonitrile and irom 1 to 20% of at least one other C-C containing .substance with from 2 to 50% on the weight of the blend of a copolymer of from 10 to 70% of acrylonitrile and from 30 to 90% of at least one other C C containing polymerizable monomer. polymeric material comprises a blend it will be a blend of a binary 'interpolymer of acrylonitrile and from 2 to 10% of another substance such as vinyl acetate, which is not receptive to dyestuffs, with a sufficient amount of a binary interpolymer of from 10 to 70% acrylonitrile and from 30 to 90% of a vinyl-substituted tertiary heterocyclic amine such as vinylpyridine or a l-v'inylimidazole, to give a dyeable blend having an overall vinyl-substituted tertiary heterocyclic amine content of from 2 to 10% on the weight of the blend. A preferred terpolymer for use in the present invention is one containing by weight in the polymer molecule, at least 2% vinyl acetate, from 90 to 94% acrylonitrile and from 4 to 8% of Z-methyl vinylpyridine. While it is preferred to employ polymers containing at least 80% by weight of acrylonitrile in the polymer molecule, other polymers may be employed in the practice of the present invention with the same desirable results, for example, polymers containing 40% or more by weight of acrylonitrile in the polymer molecule.

The invention will be more fully described in the following examples which are given by way of illustration and .not of limitation. In the examples, all parts and percents are by weight unless otherwise indicated.

Example I Example II A skein of a eopolymer of 97% ,acrylonitrile ,and 3% vinyl acetate (0.5.5 gram) was immersed in ml. of dyebafliqcontaining 2% Wool Fast Scarlet G Supra (C. I. No. 2529 and 10% sulfuric acid based on the fiber weight. To this dyebath there was added with stirring at room temperature 0.2 gram of the polymerization reaction mixture of Example I, based on the fiber weight. Immediate precipitation of the dyestutI-polyvinylimidazolc adduct on the s'kein occurred. After the mixture was heated to 50 C. for one-half hour the skein was removed and washed with water. Complete dyebafh exhaustion had occurred and the s'l-zein was dyed .a deep scarlet color.

Preferably, when a Example 111 In this example 0.3 gram of the polyvinylimidazole reaction mixture of Example I was diluted with 49.7 grams of water. 2.74 mls. of this solution was added to 25 mls. of the Wool Fast Scarlet G Supra dyebath described in Example II and containing a 0.55 gram skein of 97% acrylonitnile and 3% vinyl acetate copolymer. This ad dition was made at room temperature and the amount of polyvinylimidazole added was equivalent to 0.75% based on the weight of the skein. Rapid dyebath exhaustion occurred and when the skein was removed and Washed with water and dried, the fiber had been dyed a deep and even scarlet shade.

Example IV 0.5 gram of an emulsion copoly mer comprising 70% Z-Vinylpyridine and 30% acrylonitrile was dissolved in a mixture of 25 mL of water and 0.088 ml. of sulfuric acid. To 0.073 ml. of the aqueous solution there was added 20 mls. of 2% W001 Fast Scarlet G Supra and 10% sulfuric acid. A skein (0.45 gram) of a copolymer of 97% acrylonitrile and 3% vinyl acetate was immersed in the dyebath. The bath was slowly heated to C. and the skein was dyed an even scarlet shade. The amount of the basic copolyrner added was equivalent to 0.25% vinylpyridine (based on the fiber weight). In this case the dyebath was not completely exhausted.

Example V The .same procedure was followed as outlined in Example .IV with the exception that three times as much of the .l-vinylpyridine copolymer was employed. In this instance dyebath exhaustion occurred on heating to 45 C. and .a deep scarlet color was obtained.

Example VI A skein of polyacrylouitrile (0.5 gram) was immersed in 45 m1. ofAcid Green CC Extra Cone. (containing 4% dye and 2.0% sulfuric .acid based on the fiber weight). To this solution there was added -a 4% interpolymerized N-vinylimidazole as a N-vinylimidazole-50% acrylonit-rile copolymer in emulsion form (4/l-water/monomer ratio). The resultant dispersion was heated to C. for a ,period of one-half hour and the fiber was dyed a dark green. The skein was crock-fast after drying. A control .skcin .did not dye without the addition to the dyebath of the basic .eopolyrner.

Example VII An Alizarin light Blue dye solution containing 2% dye and 10% sulfuric acid (based on the fiber weight) with a 45/1 dyebath/fiber ratio was prepared and a .skein.

of a copolyrner of 9.7% acrylonit-rile and 3% vinyl ace tate was immersed therein. After heating the dyebath for a period of approximately one hour at .C., the fiber absorbed no dye. To this mixture, after the same had been cooled, there was added 4% iuterpolymerized vinylimidazole as a 50% -acrylonitrile=50% N-vinylimidazole copolymer in an emulsion form (4/l-water/monomer ratio). The fiber was then dyed toa deep blue shade.

To a similar dyebath as described above containing .a skein of 97% acrylonitrile and 3% vinyl acetate copolymer there was added ,polyvinylimidazole as a 0.25% aqueous solution (002 gram of polyvinylimidazole .in 7 ml. of solution, equivalent to 4% of the fiber weight). In this .case complete coagulation of the dyestutf occurred with some adherence to the fiber. I

In the present invention, the compositions from which the fibers or other structures are formed may contain various adjuvants, such as delustrants, and/or the like.

In the case of yarn to be dyed by means of :the instant invention, the same may be produced by the usual Wet or .dry spinning methods from solutions of the actylouitr'ile polymers or blends as described herein in the lcnotun solvents for the polymers such as dimethylformamidedi methylacetamide, sulfolane, etc. The filaments or yarns may be processed in the usual manner, and heat-stretched for orientation during such processing. In certain instances, as when the filaments are to be cut or otherwise reduced to staple, the heat-stretching for orientation may be omitted. In the case of fabrics to be dyed by the present process, the same may be prepared by the known textile-making processes including weaving, knitting, braiding, etc. Non-woven fabrics or felt-like structures formed from filaments or discontinuous fibers of the acrylonitrile polymers in admixture with other fibers which on heating are rendered adhesive and serve to fix the fibers in position in the structure by autogenous bonding, may also be dyed by this process.

The invention has many advantages, among a few of which are a convenient and valuble method for dyeing structures prepared from acrylonitrile polymers, and a novel method whereby ditficultly dyed acrylonitrile polymer structures can be readily dyed using standard commercial equipment. The present process greatly increases the dyebath exhaustion and the products or structures so dyed possess a deeper shade and are dyed more evenly than has been obtainable heretofore. In addition, and more important, only a very small amount of the vinyl substituted heterocyclic tertiary amine need be employed in the dyeing medium in order to produce good dyeability, namely, as little as 0.25% or 0.10%, based on the weight of the structure to be dyed. The structures dyed in accordance with the present invention have good resistance to washing and crocking. The physical and chemical properties of the dyed structures are comparable to the desired properties of the undyed structures. Numerous other advantages of the present invention will be apparent to those skilled in the art.

It is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined by the appended claims.

I claim:

1. A process for dyeing structures prepared from acrylonitrile polymers comprising at least 80% by weight of polymerized acrylonitrile, which comprises treating said structures with a aqueous dyeing medium containing an acid dye, an acid, and from 0.10 to 10% based on the weight of the structure of a basic polymer comprising a vinyl substituted tertiary heterocyclic amine selected from the group consisting of N-vinylimidazole, vinylpyridine, alkylsubstituted vinylpyridines, vinylquinoline, vinylmercaptobenzothiazole, and salts thereof, at a temperature the range from room temperature to 150 C.

2. A process as defined in claim 1 wherein the structure is prepared from an acrylonitrile polymer comprising from 80 to 98% acrylonitrile and from 2 to 20% of a polymerizable monoolefinic material.

3. A process as defined in claim 1 wherein the structure is prepared from an acrylonitrile polymer comprising 97% acrylonitrile and 3% vinyl acetate by weight.

4. A process for dyeing structures prepared from acrylonitrilc polymers comprising at least 80% by weight of polymerized acrylonitrile, which comprises treating said structures with an aqueous dyeirig medium containing an acid dye, an acid, and from 0.10 to 10% based on the weight of the structure of a basic polymer comprising a vinyl substituted tertiary heterocyclic amine selected from the group consisting of N-vinylimidazole, vinylpyridine, alkyl-substituted vinylpyridines, vinylquinoline, vinylmercaptobenzothiazole, and salts thereof, at a temperature in the range from 60 to 150 C.

5. The process as defined in claim 4 wherein the basic polymer is polyvinylimidazole.

6. The process as defined in claim 4 wherein the basic polymer is polyvinylpyridine.

7. The process as defined in claim 4 wherein the basic polymer is a 50% acrylonitrile and 50% N-vinylimidazole copolyrner.

8. The process as defined in claim 4 wherein the basic polymer is polyvinylpyridine hydrochloride.

9. The process as defined in claim 4 wherein the basic polymer is polyvinylpyridine sulfate.

References Cited in the file of this patent UNITED STATES PATENTS 2,168,336 Heckert Aug. 8, 1939 2,527,863 Webb Oct. 31, 1950 2,603,621 Craig July 15, 1952 FOREIGN PATENTS 613,817 Great Britain Dec. 3, 1948 

1. A PROCESS FOR DYEING STRUCTURES PREPARED FROM ACRYLONITRILE POLYMERS COMPRISING AT LEAST 80% BY WEIGHT OF POLYMERIZED ACRYLONITRILE, WHICH COMPRISES TREATING SAID STRUCTURES WITH A AQUEOUS DYEING MEDIUM CONTAINING AN ACID DYE, AN ACID, AND FROM 0.10 TO 10% BASED ON THE WEIGHT OF THE STRUCTURE OF A BASIC POLYMER COMPRISING A VINYL SUBSTITUTED TERTIARY HETEROCYCLIC AMINE SELECTED FROM THE GROUP CONSISTING OF N-VINYLIMIDAZOLE, VINYLPYRIDINE, ALKYL-SUBSTITUTED VINYLPYRIDINES, VINYLQUINOLINE, VINYLMERCAPTOBENZOTHIAZOLE, AND SALTS THEREOF, AT A TEMPERATURE IN THE RANGE FROM ROOM TEMPERATURE TO 150* C. 